What Goes Into Naming the Cause of a Disease?

This week, the disease caused by the novel coronavirus was officially named COVID-19 by the World Health Organization (WHO). COVID stands for COrona VIrus Disease, and 19 is for 2019, the year it was first identified. The virus itself has been named “novel coronavirus” by the media and others since it was first identified, but its official name is 2019-nCoV. Like in naming the disease, the virus’ name is a variation of the year it was detected and the virus itself.

Diseases that have been known for centuries have kept their classical names even after the viruses, bacteria or fungi that cause them were first identified. For example, measles has been called by its name for centuries, but it was not until 1954 that the virus that causes measles was identified in a laboratory in Massachusetts. (Measles and German Measles — rubella — were believed to be caused by the same microscopic agent up until 1814, and rubella was not named that until 1866.)

Because of advancements in genetic technology, the genomes of disease-causing viruses can now be understood quite quickly after isolating the virus. Like we do for other organisms, viruses have been classified into Realm, Phylum, Class, Order, Family, Subfamily and Genus. In the case of measles, the genus is Morbillivirus; subfamily is Orthoparamyxovirinae; family is Paramyxoviridae; order is Mononegavirales; class is Monjiviricetes; phylum is Negamaviricota; and realm is Riboviria.

If some of those scientific names seem familiar to you, it might be because you’ve seen variations of them in other viruses or because scientists have used those names to describe other viruses that cause human disease. For example, Ebola, mumps, Nipah and rabies are all in the order Mononegavirales. So, yes, they are somewhat related, but you can probably guess that a vaccine against one doesn’t give immunity for another.

Interestingly, scientists do not hold retroviruses (like HIV) to be in the same realm as viruses. Retroviruses are said to be of incerta sedis, meaning “of uncertain placement.” The reasons for this are a little complicated, but it boils down to the fact that they have a different method of infecting host cells compared to the methods used by other viruses. So it is difficult to place them in one particular realm, phylum or class.

Many viruses are also named based on the location where they were first identified or where they first caused disease. Ebola is named after the Ebola river in the Democratic Republic of the Congo. It was in Yambuku that the first well-documented and researched outbreak of Ebola happened in 1976, although an outbreak in Nzara, Sudan, in the same year is also known now to have been caused by Ebola.

There is also a virus with no name. Well, it has a name, but its name is Sin Nombre, which is Spanish for “no name.” It was named this because of politics, really. The virus is really a hantavirus isolated from rodents in the Four Corners region of the United States. When it was first identified, the governments of the four states in the area did not want the virus associated with them, according to Virus Hunter, an autobiography by renowned epidemiologist CJ Peters, MD. In his autobiography, Dr. Peters explained that the Centers for Disease Control and Prevention (CDC) settled on sin nombre as a compromise to not name the virus after where it was first identified and as a bit of a joke about a virus with no name because no one would name it.

Hantavirus, by the way, is named after the Hantan River in South Korea, and it is the virus mostly associated with high death rates (5% to 15%), but it is second to Sin Nombre in that regard. Sin Nombre has estimated death rates of up to 50%, though there have been relatively few cases.

Dr. Peters also investigated an outbreak of a viral hemorrhagic fever in South America. When viewed under the microscope, that virus seemed to have very tiny grains of sand inside of it. (It was not sand. It was small proteins.) Because of that, it was named arenavirus. “Arena” is Spanish for sand. (Arenas where special events take place are named after the special events places in Ancient Rome where sand covered the area where gladiators fought or other entertainment events happened.)

More recently, influenza viruses have been given the names of their first identification as part of a larger naming convention used to identify them. Type A influenza viruses are named in a way that includes their type, their Hemagglutinin and Neuraminidase (proteins) designations, and the year and location where they were first identified. The virus that caused the 2009 pandemic was named “A/California/7/2009(H1N1)pdm”.  In that name, “pdm” stands for “pandemic Mexico.”

As humans expand their domain over wild areas of the world, we are going to come into contact with viruses, bacteria, fungi and parasites that cause disease. As we see in China and have seen in Africa, these encounters may trigger outbreaks of severe disease. Part of combating these diseases is using communication, and these diseases and their causes need names that can communicate their nature. Very often, we have used a variation of the location where they were first identified. More recently, we have begun adopting a more uniform system of classifying and naming these microbes and the diseases they cause. Time will tell if COVID-19 and nCoV-19 will really stick to our collective subconscious or if “Wuhan virus” or “novel coronavirus” will remain.

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Author: René F. Najera, DrPH

I am the editor of the History of Vaccines site, an online project by the College of Physicians of Philadelphia. All opinions expressed on these blog posts are not necessarily those of the College or any of my employers. Check out my professional profile on LinkedIn: https://www.linkedin.com/in/renenajera Feel free to follow me on Twitter: @EpiRen

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